Conventionally, an upright piano of the above-mentioned type has been disclosed e.g. in Patent Literature 1. This upright piano is a silent piano which is played while switching between a normal playing mode in which playing is performed using acoustic tones and a silent playing mode in which playing is performed using electronic tones. The silent piano includes keys, hammers each of which pivotally moves in accordance with depression of an associated key, a first shutter provided for each key, a first optical sensor disposed below the first shutter, a second shutter provided for each hammer, and second and third optical sensors disposed at a location close to the turning path of the second shutter, and so forth. The first to third sensors are connected to a musical tone generator.
In the silent playing mode, as the hammer pivotally moves in accordance with key depression, the first shutter blocks the optical path of the first optical sensor, and the second shutter blocks the optical paths of the respective second and third optical sensors, whereby detection signals corresponding to the operations of the respective shutters are output from the respective first to third optical sensors to the musical tone generator. The musical tone generator sets sounding timing and a tone volume based on the detection signals from the second and third optical sensors, and sounding stop timing based on the detection signal from the first optical sensor, and generates a musical tone based on these set control parameters.
Further, in general, an upright silent piano is provided with a soft pedal for giving a soft pedal effect in the normal playing mode though it is not described in Patent Literature 1. The soft pedal is connected to a pivotally movable hammer rest rail via a pedal lever and a pedal rod, and in a key-off state of a key, the hammers are held in contact with the hammer rest rail. When the soft pedal is stepped on, the hammer rest rail is pushed up and pivotally moves toward the strings, whereby the position of each hammer in the key-off state (hereinafter referred to as “the key-off position of the hammers”) approaches the associated string. As a consequence, the distance between the key-off position of the hammer and the string (hereinafter referred to as “the hammer stroke”) becomes shorter, whereby the soft pedal effect can be obtained in the normal playing mode.
In the conventional silent piano constructed as above, when the soft pedal is stepped on in the silent playing mode, the motion of the hammer rest rail caused by the step-on of the soft pedal causes the key-off position of the hammer, i.e. the initial position of the hammer that pivotally moves in accordance with key depression, to approach the string, and hence timing in which the second shutter provided for the hammer blocks the optical paths of the respective second and third optical sensors differs from original blocking timing in a non-stepped-on state of the soft pedal. This makes it impossible to appropriately set sounding timing and a tone volume based on detected blocking timing, and therefore, there is a fear that silent playing cannot be properly performed.
The present invention has been made in order to solve the above problem, and an object thereof is to provide an upright piano which is capable of providing a soft pedal effect by step-on of a soft pedal in a first playing mode for performing acoustic playing, and an excellent performance in a second playing mode even when the soft pedal is stepped on, without being affected by the step-on of the soft pedal, while properly detecting the rotational position of each hammer.
[Patent Literature 1] Japanese Laid-Open Patent Publication (Kokai) No. 2007-79312